Investigating Magnetic Source Depths In The Soutpansberg Basin, South Africa

Abstract

The Limpopo Province of South Africa has thermal manifestations in the form of hot springs. The Soutpansberg Basin hosts several hot springs and is located in the north-eastern part of the Limpopo Province. Research was undertaken in order to understand the geothermal potential of the area. Airborne magnetic data was analyzed. Methods that were used to determine magnetic source depths were Radial Averaged Power Spectrum, Euler De-convolution and the Tilt Derivative. The magnetic source depth, at which crustal rocks reach a temperature where spontaneous magnetization is lost, is assumed to be the heat source depth and is called the Curie depth. Mapping of Curie depths is based on the estimation of the depth to the bottom of magnetic bodies. The depth to the bottom of magnetic sources in the vicinity of thermal manifestations was found to be in the range 2 km to 5 km. The deepest zones at 8 km to 10 km depths are located to the west and east of the basin. The deep seated north-south oriented structures could be related to the East Africa Rift fracture system. Depth solutions that were obtained using the Radial Average Power Spectrum were comparable to Euler depth solutions. The Tilt Derivative results confirmed the presence of shallower source depths below areas that had thermal manifestations. Results of the investigation have shown that regions with shallow Curie isotherm depths are potential targets for geothermal investigations.